Tamarind (tamarindus indica) is a widely grown tree found in the tropical countries, the fruits of which contain as much as 10-15% of L(+) tartaric acid depending on the source of origin and the stage of muturation of the fruit. It therefore is a potential source for the recovery of tartaric acid. Efforts to recover tartaric acid from tamarind pulp in the past were based on the treatment of pulp extract with calcium hydroxide and subsequent acidification of calcium tartarate which generated tartaric acid and calcium sulfate. These methods suffered from the drawback that pectin also gets precipitated in the form of calcium pectate along with calcium tartarate which was extremely difficult to separate from calcium tartarate. Alternatively, L(+) tartaric acid was recovered from the tamarind pulp by aqueous extraction followed by treatment with ion exchange resins. Ion exchange methods adopted in the past suffered from the limitation that rapid fouling of the columns occurred making the recovery of the tartaric acid economically unattractive. This was because other ingredients present in the tamarind pulp which can foul the column were not removed prior to the ion exchange treatment.
In the our co-pending Indian Patent Application No.857/Del/96 (not published) filed by the applicants a process for the recovery of tartaric acid, potassium bitartarate, pectin, and fruit sugar from tamarind pulp has been described. The process enables the recovery of four products of commercial value from tamarind pulp, not hitherto commercially exploited for the recovery of potassium bitartarate, tartaric acid, pectin and fruit sugar. Hence, the said process is economically more competitive that other conventional processes employing wine argols for the recovery of potassium bitartarate, tartaric and pectin and sugar. The process is devised such that the recovery of each of the subsequent products is simplified to a great extent. Each product is recovered in high purity so as to meet the specification of the food and pharmaceutical industry. However, the disadvantage of this process is that the tartaric acid is first recovered as calcium tartarate which is subsequently acidified. This yields tartaric acid along with calcium sulphate as a by-product posing waste disposal problems. On the other hand, the process of the present invention does not pose any such problems. The process of the present invention is environment friendly, economical and simple.
Another co-pending U.S. patent application Ser. No. 08/907,891 filed by the Applicants also relates to a process for the recovery of tartaric acid from tamarind pulp. In the process described in this application, tamarind pulp was extracted in water. The aqueous solution was decolorized. It was concentrated and potassium tartarate was separated and recovered as a residue. The aqueous solution was then treated with an organic solvent to precipitate pectin, which was separated and purified. The organic solvent was then evaporated and the remaining aqueous solution was diluted and extracted into an organic layer, recovered the aqueous layer by adding the water and raising temperature to 50.degree. C.-80.degree. C. This aqueous solution was then concentrated and tartaric acid recovered by crystallization. The aqueous raffinate from solvent extracts was passed over ion exchange resin and concentrated to obtain fruit sugars. The present patent application describes an improved process for recovery of potassium bitartarate, pectin, sugars and tartaric acid from tamarind pulp wherein the steps of recovery of value added products from tamarind pulp is simplified. The process becomes economically more attractive. The process of recovery of value added products eliminates the efforts involved in self extraction in organic layer, transfer, aqueous layer, recovery of their organic layer and solvent recovery step.
It is now observed that all above-mentioned stages can be eliminated by using a simple process which is more economical and viable. The said process can also be performed easily without costly apparatus.